import React from 'react'
import { Upload, Button } from "antd"
import * as XLSX from "xlsx"

export default function Main() {
  const handleExportAll = (e) => {
    //导出的表头
    const entozh = {
      "name": "姓名",
      "age": "年龄",
      "address": "地址"
    }

    //导出数据
    const nowdata = [{name:"xiaowang",age:1,address:"武侯区"}]

    //构造数据
    const json = nowdata.map((item) => {
      return Object.keys(item).reduce((newData, key) => {
        const newKey = entozh[key] || key
        newData[newKey] = item[key]
        return newData
      }, {})
    });
    
    //
    const sheet = XLSX.utils.json_to_sheet(json);

    openDownloadDialog(sheet2blob(sheet, undefined), `table.xlsx`);

  }
  const openDownloadDialog = (url, saveName) => {
    if (typeof url == 'object' && url instanceof Blob) {
      url = URL.createObjectURL(url); // 创建blob地址
    }
    //超链接，浏览器默认超链接自带下载功能
    var aLink = document.createElement('a');
    aLink.href = url;
    aLink.download = saveName || ''; // HTML5新增的属性，指定保存文件名，可以不要后缀，注意，file:///模式下不会生效
    var event;
    if (window.MouseEvent) event = new MouseEvent('click');
    else {
      event = document.createEvent('MouseEvents');
      event.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
    }
    aLink.dispatchEvent(event);
  }
  /**
   * 将创建sheet对象，转化为二进制数据blob
   * @param {*} sheet 
   * @param {*} sheetName 
   * @returns 
   */
  const sheet2blob = (sheet, sheetName) => {
    sheetName = sheetName || 'sheet1';
    var workbook = {
      SheetNames: [sheetName],
      Sheets: {}
    };
    workbook.Sheets[sheetName] = sheet; // 生成excel的配置项

    var wopts = {
      bookType: 'xlsx', // 要生成的文件类型
      bookSST: false, // 是否生成Shared String Table，官方解释是，如果开启生成速度会下降，但在低版本IOS设备上有更好的兼容性
      type: 'binary'
    };
    var wbout = XLSX.write(workbook, wopts);
    //JS中存放二进制数据的容器
    var blob = new Blob([s2ab(wbout)], {
      type: "application/octet-stream"
    });
    // 字符串转ArrayBuffer
    function s2ab(s) {
      //缓冲区，里面可以处理blob数据
      var buf = new ArrayBuffer(s.length);
      var view = new Uint8Array(buf);
      for (var i = 0; i != s.length; ++i) view[i] = s.charCodeAt(i) & 0xFF;
      return buf;
    }

    //最终处理好的二进制数据
    return blob;
  }
  return (
    <div>
      <Button type="primary" onClick={handleExportAll}>Excel导出数据</Button>
    </div>
  )
}
